Apart from the obvious cocks, dildoes and vibrators in later life, the first thing I can remember shoving up my arse, was a large safety pin (4" maybe?), when I was 7 years old. Unfortunately, I put it in with the head end first and without any kind of lube, so when I tried to pull it out, the sharp metal edge hurt too much and I couldn't get it out! I couldn't figure out what to do, so I went into my sisters' bderoom for help. They would have been 9 and 4 then and both in bed, as I had been. I pulled down my pyjama bottoms and parted my cheeks to show them the safety pin poking half out of my chocolate starfish. They started laughing their heads off, and soon our mum came upstairs to find out what all the noise was, as we were supposed to be in bed. Mum was laughing too, and took me back into my bedroom to try and retrieve the safety pin. I had to lie on the bed, on my back, with my knees up by my chin. She tried to wiggle it out but I was wincing too much, so she called downstairs to ask dad to come up and bring the butter dish with him. Then I had both of them kneeling down beside my bed, fingering my arsehole with butter, trying to get the safety pin out, without ripping my sphincter to shreads! They were laughing so much, it took them about 20 minutes to remove it. My dad said to me "I bet you won't be doing that again, in a hurry!"
My parents are both dead now but I sometimes wonder whether my sisters remember that incident. I'm not going to ask them! Even though that was before puberty, perhaps I was already gay at that age and exploring my nether regions for pleasure, or do all children experiment like that? I remember my friend telling me, a few years ago, that she left her two girls playing in the bath together, when they were under 6 years old. When she came back to check on them, she found the older one trying to stick the Fructis shampoo bottle up her velvet tardis!